1. Field Of Invention
The present invention generally relates to the art of pressurized fuel gas encapsulation. More specifically, the invention teaches a method and apparatus for maximizing the charge of low density powdered adsorbent into a high pressure fuel gas storage bottle.
2. Prior Art
It is known to those with skill in the prior art of fuel gas use and distribution that certain adsorbents, such as activated carbon, have an affinity for natural gas, propane and many other hydrocarbons. The system of U.S. Pat. No. 4,749,384 to J. J. Nowobilski et al is representative. Such affinity may be exploited by charging pressurized gas storage bottles or cylinders with adsorbent prior to a charge of fuel gas. This procedural device permits a lower confinement pressure for a given weight of gas within the fixed volume confinement of the bottle: an extremely significant safety and economic advantage.
High pressure, 2000 psi and greater, industrial gas bottles are predominately fabricated from steel using numerous welding, normalizing, heat treating and testing procedures. For this reason, it is not practical to charge a bottle with adsorbent before the last step of the fabrication process is complete. Conversely, for structural reasons, these bottles are made with a single, small diameter opening at one axial end of about one inch diameter. This single opening is used for both filling and extracting the fuel gas. Accordingly, this bottle filler opening constitutes a physical limitation on the absorbent characteristics and the rate of adsorbent charging.
Under these conditions and limitations, it has been the existing state of the art to charge industrial bottles with granular or pelletized forms of adsorbent: notwithstanding the fact that considerable density or volumetric efficiency is sacrificed in comparison to the theoretically possible density of powdered adsorbent.
Although powdered activated carbon is theoretically a superior industrial bottled gas adsorbent, it has, in the past, been an impractical material for this use. Due to an extremely fine particle size, 3 to 90 microns and a low density of less than 30 pounds per cubic foot, the material tends to aerate when transported in a flow stream. For example, a typical wood-based powdered activated carbon may have a packed bulk density of 28 pounds per cubic foot. After aeration by flow transport, however, the bulk density is reduced to 12 to 16 pounds per cubic foot: a 50% loss of density. Translated in terms of gas adsorption capacity, industrial gas bottles of a given volumetric capacity, due to aeration, may be filled to only 50% of packed capacity. Consequently, the quantity of fuel gas adsorbed on such a bottled carbon bed is restricted accordingly.
It is an objective of the present invention, therefore, to provide a process for filling an industrial gas bottle with a bed of powdered activated carbon packed to bulk density that is 90 to 95% as dense as is theoretically possible for the particular carbon.
Another objective of the present invention is to provide a process for continuously flowing low density powdered, adsorbent into an industrial gas bottle within a totally enclosed and dustless atmosphere.
Another objective of the present invention is to provide a process for filling standard industrial gas bottles with low density powdered, adsorbent within an elapsed time of only 2 to 10 minutes.
Another objective of the present invention is to provide a manifold filling line for flowing low density powdered, adsorbent simultaneously into several industrial gas bottles.
Another objective of the present invention is to provide an apparatus for drawing low density powdered, adsorbent into the closed confinement of an industrial gas bottle.
Another objective of the present invention is to provide an apparatus for simultaneously drawing a flow stream of low density powdered, adsorbent into an industrial gas bottle and compacting the accumulated bed to as much as 95% of a maximally compacted adsorbent bed.